You don’t need a huge wrench when working with the p-trap under the sink and water wont start spraying everywhere either as drains aren’t pressurized.

Sprinklers react to heat, not smoke.

Not all spriklers go off at the same time in most systems. Only the sprinkler heads affected by heat.

The water coming out of sprinklers initially isn’t clear but dark, rusty sludge. Sometimes even black as ink.